JPH01149A - Method for producing carbon-filled silane-grafted polyolefin - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for producing a silane-grafted polyolefin used for outdoor electric wires that require weather resistance, and particularly relates to a method for producing a silane-grafted polyolefin that is used for outdoor electric wires that require weather resistance. Polyolefin with excellent appearance.

The present invention relates to a method for producing carbon-filled silane-grafted polyolefins with properties.

[Prior Art and Problems to be Solved by the Invention] Conventionally, a silane compound having a hydrolyzable silyl group and a double bond in its molecule is treated in the presence of an organic peroxide such as dixyl oxide. A silane-grafted polyolefin obtained by grafting a polyolefin is crosslinked by reacting with moisture in the presence of a silanol condensation catalyst such as dibutyltin dilaurate, and is used in many fields as a crosslinked polyolefin.

Among these, crosslinked polyolefins used for outdoor electric wires require carbon filling in the polyolefin in order to obtain weather resistance, but since carbon inhibits silane grafting of polyolefins, sufficient grafting of polyolefins is not possible. Therefore, there was a drawback that only a crosslinked polyolefin with a low degree of crosslinking could be obtained. Therefore, in order to avoid inhibition of carbon grafting, a silane-grafted polyolefin, which is obtained by grafting a carbon-free polyolefin with an organic peroxide and a silane compound, and a masterbatch containing carbon and a silanol condensation catalyst are mixed during molding. However, in the molded products obtained by this method, the silane-grafted polyolefin and the carbon masterbatch could not be mixed sufficiently, and the carbon was not evenly dispersed or the appearance was uneven. When the amount of carbon in the masterbatch increases, water in the carbon causes foaming, so there is a drawback that pretreatment such as removal of water is required.

In order to overcome such conventional difficulties, the present invention aims to produce a carbon-filled silane-grafted polyolefin in which a polyolefin is sufficiently silane-grafted and carbon is uniformly dispersed in the silane-grafted polyolefin.

[Means for Solving the Problems] In order to achieve the above object, the present invention mixes particulate polyolefin and carbon, and then grafts the mixed polyolefin with silane to produce a silane-grafted polyolefin. The method is characterized in that the silane-grafted polyolefin and the carbon are mixed together so that they are uniformly dispersed.

[Function] The method for producing the carbon-filled silane-grafted polyolefin of the present invention will be described in detail below.

The polyolefins used in the present invention include low polyolefins such as high density, medium density, and low density polyethylene, polypropylene, chlorinated polyethylene or ethylene propylene rubber, copolymers thereof, and chlorinated products thereof. Preferably 0.0 of a radical generator such as hydroxypeptyl oxide or dicumyl peroxide is added to the polyolefin.
1 to 2.0 weight percent, and an unsaturated silane compound having a hydrolyzable silyl group, such as vinyltrimethoxysilane or vinylethoxysilane, is added to 0.1 to 5.0 weight percent. The carbon content of the filler is 0.2 to 2 weight percent. The method for silane grafting of carbon-filled polyolefins is to supply a master patch made of a tri-blend of polyethylene and carbon, a radical generator, and a silane compound to a device having a heating crosslinking function such as an extruder, and perform a crosslinking reaction between polyolefins by controlling the temperature. The temperature is raised to above the melting point of the polyolefin while suppressing the temperature, and as a first step, the polyolefin, radical generator, and unsaturated silane are sufficiently kneaded. At this time, by making the screw of the extruder have deep grooves, the polyolefin, radical generator, and unsaturated silane are sufficiently mixed, but although carbon is mixed with the polyolefin macroscopically, it is not mixed sufficiently microscopically. However, it is localized in the polyolefin. By rapidly increasing the temperature in this state, the polyolefin can be effectively grafted with silane without being inhibited by carbon. After the grafting reaction has started, in the second step, the extruder screw is kneaded in a shallow groove that satisfies complete mixing, so that carbon can be completely and uniformly dispersed in the silane-grafted polyolefin. be.

[Example code] The following will be explained based on examples.

The extruder shown in the figure is a schematic representation of an apparatus useful for carrying out the invention, and is an extruder E having a screw S consisting of a deep groove zone A, a grafted zone B, and a shallow groove zone C. Polyethylene and carbon were put into the hopper H of the extruder E in an amount of 0.8% by weight relative to the polyethylene, and 0.07% by weight of dimethyl peroxide and 2.0% by weight of vinyltrimethoxysilane were dropped at the hopper mouth HM. The temperature was raised to 130° C. or higher to thoroughly mix polyethylene, dimethyl peroxide, and vinyltrimethoxysilane in the deep groove region A of the screw S. After that, the temperature is raised to 210°C, and after grafting is carried out in the grafting region B, the carbon and silane-grafted polyethylene are completely kneaded in the shallow groove region C of the screw S, and the carbon is uniformly mixed into the silane-grafted polyethylene. It was dispersed into The molded product was crosslinked in the presence of a silanol condensation catalyst, and the degree of crosslinking, tensile strength, and tensile elongation were measured. The results are shown in the table.

As a comparative example, the degree of crosslinking, tensile strength, and tensile elongation of silane-crosslinked polyethylene (corresponding to Comparative Example A in the table) obtained by simultaneously kneading dimethyl peroxide and vinyltrimethoxysilane with conventional carbon-filled polyethylene were measured. . In addition, as another comparative example, dimethyl peroxide and vinyl methoxysilane were added to polyethylene to graft the polyethylene, and then a masterbatch containing carbon and a silanol condensation catalyst was mixed to obtain silane-crosslinked polyethylene (as shown in the table). (corresponds to comparative example B)
The degree of crosslinking, tensile strength and tensile elongation were measured. The results are shown in the table.

Blank space below [Effects of the Invention] As described above, according to the present invention, a radical generator and an unsaturated silane are reacted with a polyolefin in which carbon is unevenly dispersed to form a silane-grafted polyolefin, and then Since the polyolefin is kneaded, the grafting reaction of the polyolefin is sufficiently carried out without the grafting reaction being inhibited by the carbon. Moreover, carbon can be dispersed evenly.

In addition, since it has an excellent appearance, it is particularly effective for use in electric wires and the like that require excellent weather resistance.

[Brief explanation of drawings]

The figure is a diagram showing an apparatus used in an embodiment of the present invention. E・・・Extruder S...Screw H...Hopper HM...hopper mouth A... Deep groove area B... Grafting area C... Shallow groove area D...Extrusion port

Claims (1)

[Claims] After mixing particulate polyolefin and carbon,
Silane grafting the mixed polyolefin,
A method for producing a silane-grafted polyolefin, which comprises producing a silane-grafted polyolefin, then kneading the silane-grafted polyolefin and the carbon to uniformly disperse the carbon in the silane-grafted polyolefin.